iStock/Thinkstock(NEW YORK ) — At least five people have died and more than 3,000 U.S. flights have been canceled due to a massive winter storm hitting the East Coast, with heavy snow, gusty winds and the coldest air of the season.

State officials said three of the deaths occurred in North Carolina and a fourth happened in South Carolina, as the weather system barreled up the eastern coast.

Among those killed were two men whose pickup truck slid off a road and overturned into a creek Wednesday night, North Carolina Gov. Roy Cooper said at a press conference Thursday morning. The storm has also caused hundreds of car crashes around the Tar Heel state, Cooper said.

A fifth person was killed by a snowplow in Hampton, Virginia, local police said. A 75-year-old man was clearing snow from a business parking lot when he suffered life-threatening injuries from the snowplow, police said.

Meanwhile, U.S. airlines canceled at least 3,731 flights within, into and out of the United States Thursday and delayed 1,401 others, according to airline tracking firm FlightAware. Most of the cancellations were in New Jersey, Boston and New York, where some areas could get one to three inches of snow per hour starting this morning.

Major cities along the East Coast — from North Carolina to Maine — were under blizzard warnings, while others were placed under winter storm warnings.

“A powerful Nor’easter will move north along the East Coast through Thursday,” the National Weather Service said in a statement. “Reinforcing Arctic air and gusty winds will sweep in behind the Nor’easter for the coldest wind chills of the season in many eastern locations.”

Maine Gov. Paul LePage announced that all state offices will be closed Thursday. New Jersey Gov. Chris Christie also closed all state offices and declared a state of emergency in three coastal counties.

ABC News meteorologists spotted lighting on the radar Thursday morning in Long Island, New York, as well as parts of Connecticut, which means residents there could be experiencing thundersnow. The rare weather phenomenon results in the unusual combination of thunder and lighting during a snow storm.

As this coastal snow storm moves over the warm waters of the Gulf Stream, the weather system is drawing moist, warm air into the atmosphere. That warm air rises and forms into a cloud where cold and warm air meet, producing turbulence that’s needed for lightning to form. The water droplets and ice crystals inside the cloud bump together and move apart in the air, creating static electric charges in the clouds, according to meteorologists.

The storm has already brought record snowfall to cities like Tallahassee, Florida, where residents got the most snow since 2010, and Charleston, South Carolina, which received more than five inches of snow, breaking the record set in 1989.

Meanwhile, some areas between Georgia and Virginia were blanketed with up to half a foot of snow by Thursday morning. A foot of snow was recorded in Atlantic County, New Jersey, by Thursday afternoon.

“This will be a rapidly strengthening storm that is expected to produce strong winds and minor to moderate coastal flooding,” the National Weather Service said Wednesday after warning that the storm could result in downed trees and power outages along the East Coast.

Snowfall in Boston should let up Thursday evening, while the areas surrounding New York City should get some relief by midnight, meteorologists said.

But winds are expected to increase as the storm picks up off the coast of New England and “bombs out,” meteorologists said, referring to the term bombogenesis, which occurs when a storm system undergoes a quick drop in atmospheric pressure and strengthens.

Wind gusts are forecast to come in between 40 to 60 mph along most parts of the East Coast this afternoon, but some areas, including Atlantic City, New Jersey, could see gusts above 70 mph.

Separately, the coldest air of the season is forecast to spill from Canada into the eastern United States, bringing wind chills to as low as one degree in some major cities, including Washington, D.C., and New York City.

The worst of the cold will be in the Northeast Friday morning, when wind chills are forecast to hit the minus 40s in New England.